1. Field of the Invention
This invention relates to a method of making 3-amino-2-hydroxy-2-cyclopentenones substituted in the 4-position with an alkyl group, particularly, a "bulky" alkyl group, e.g., a higher alkyl group containing more than 6 carbon atoms.
2. Description of the Prior Art
A variety of reductone compounds including amino reductones are known, and a number of such compounds have been used as reagents in photography. For example, U.S. Pat. No. 3,690,872 is directed to the use of certain amino hydroxy cycloalkenones as silver halide developing agents including 3-amino-2-hydroxy-2-cyclopentenones and 3-amino-2-hydroxy-2-cyclohexenones substituted in the 4-position with alkyl containing 1 to 5 carbon atoms. As discussed in this patent at column 3, lines 14-75, the preparation of 2-hydroxy-3-morpholino-2-cyclohexenone is typical of the method of preparing the amino hydroxy cycloalkenone developing agents and comprises refluxing equimolar amounts of morpholine, 3-chloro-1,2-cyclohexanedione and triethylamine in anhydrous ethyl acetate under an atmosphere of nitrogen.
Though it may be possible to synthesize 4-higher alkyl-3-chloro-2-hydroxy-2-cyclopentenone starting materials for the aforementioned substitution reaction, on the basis of our experience with a 4-undecyl-3-bromo compound it is believed that the substitution reaction would be unsuccessful. We have found that 3-bromo-2-hydroxy-4-n-undecyl-2-cyclopentenone is an exceptionally unreactive compound and that the bromine cannot be removed either by hydroysis or aminolysis without causing extensive decomposition. Indeed, with the bulky alkyl group, the conventional syntheses for these compounds are generally unsuitable.
The synthesis of .alpha.-methylglutaric acid by reacting cyanoacetamide and acetaldehyde to give .alpha.,.alpha.'-dicyano-.beta.-methylglutaramide followed by hydrolyzing the amide with hydrochloric acid to give the product has been described by R. E. Kent and S. M. McElvain, Organic Synthesis, John Wiley & Sons, Vol. 3 (1955), pages 591-593. The reaction of carboxylic acids esters with sodium in inert solvents in the presence of trimethylchlorosilane has been reviewed by K. Ruhlmann, Synthesis, 1971, pages 236-253 and as disclosed therein at pages 242-243, this reaction when applied to glutaric acid diethyl ester yields 1,2-bis-(trimethylsiloxy)-cyclopentene. See also, U. Schrapler and K. Ruhlmann, Chem. Ber., 97, pages 1383-1389 (1964) for the reaction of trimethylchlorosilane with glutaric and other aliphatic dicarboxylic acid esters in the presence of sodium.
The use of cupric salts in the oxidation of ketols is known. For example, the oxidation of 2-hydroxycyclodecanone using cupric acetate/acetic acid to yield 1,2-cyclodecanedione has been reported by A. T. Blomquist and A. Goldstein, Organic Syntheses, John Wiley & Sons, Vol. 4 (1963), pages 838-839. The preparation of 1,2-cyclohexanedione monoxime by passing ethyl nitrite gas into a mixture of cyclohexanone and hydrochloric acid has been reported by M. Murakami and Y. Yukawa, Mem. Inst. Sci. Ind. Research Osaka Univ., 5, 150 (1947); Chem. Abstr., 47, 2714. Using isoamyl nitrite, D. C. Batesky and N. S. Moon, J. Org. Chem., 1959, 24, pages 1694-1695, have prepared the symmetrical dioximino ketones of cyclohexanone and its 4-methyl derivative.